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Lead-acid batteries were tested at the National Battery Test Laboratory at Argonne National Laboratory to determine the effects on the range of an electric vehicle of rest periods introduced during the vehicle use. Rest periods ranging from zero through four hours were chosen to simulate no break, a coffee break, a lunch break, and a work break. Preliminary results suggest that no increase in range can be expected as a result of the rest periods regardless of their length; moreover, it appears that in some cases a slight loss in battery capacity, and therefore in range, may occur as the battery cools during the rest period. Similar testing of the nickel/iron battery system is now underway.

The technique used for measuring peak power available from a battery during a discharge sustained for a limited duration of time is developed and presented. In tests performed on nickel/ iron, nickel/zinc, and lead-acid electric-vehicle batteries at the National Battery Test Laboratory, it was shown that available peak power decreases with increasing depth-of-discharge (DOD). Most batteries tested deliver between 70 W/kg and 130 W/kg at 50% DOD but produce these peak powers with currents on the order of 700 A--a current well above the capability of most state-of-the-art electric-vehicle propulsion systems.

Chopper-type controllers commonly used in electric vehicle propulsion systems impose pulsed-current discharge conditions on the battery that influence both its internal power losses and available energy. In order to optimize propulsion system design, those discharge parameters that affect battery performance must be understood and characterized. In a series of tests performed on Exide EV-106 and EE-IV lead-acid traction batteries, a range of operating values were examined for current pulse frequency, average current discharge rate and pulse-to-average current level ratio. For each test, one parameter was selected as the variable while the other two parameters were maintained at fixed levels. Constant-current discharges were periodically performed during each test to relate battery performance for equivalent pulsed and constant current discharge conditions.

Standard test procedures used for electric-vehicle battery testing at the National Battery Test Laboratory at Argonne National Laboratory are described. The testing falls into two general categories--performance characterization and life-cycle testing. Activities within these categories include receipt, inspection, and installation of batteries, pretest conditioning, capacity verification, general open-circuit stand testing, partial depth-of-discharge testing, specific energy vs. specific power testing, simulated electric-vehicle profile testing, peak-power measurements, and life-cycle testing. General descriptions are provided for all tests; further detail is provided for the simulated electric-vehicle profile tests. The results from these simulated electric-vehicle profile tests are presented for a variety of lead-acid, nickel/iron, and nickel/zinc batteries.

This paper presents the results of testing and evaluation of GE/Globe EV-1300 lead-acid modules developed by Globe Battery Division of Johnson Controls, Inc. for the hybrid vehicle, HTV-1, developed by General Electric (GE) for the Department of Energy. The design of this battery was derived from that of the Globe Improved State of the Art (ISOA) battery under development for the ETV-1 all-electric vehicle. Key differences in the battery performance requirements for the HTV-1 hybrid vehicle, as opposed to the ETV-1, are higher specific power [137 W/kg versus 104 W/kg sustained for 15 seconds at 50% depth of discharge (DOD)] and less specific energy (36.1 Wh/kg versus 37.5 Wh/kg at a 3h discharge rate). Higher battery power is required for two reasons. First, in HTV-1, the battery is a smaller mass fraction of the design vehicle (341 kg battery/∼1800 kg vehicle = ∼0.19) compared to the ETV-1 (488 kg battery/∼1660 kg vehicle = ∼0.29).